You won't get any bonus points for leakage though. LM317 is 1mA or something, so your LiIon will bleed down fairly quickly (~weeks?).
There are precision low current references that run at microamperes. If you can find an adjustable one, you can get what you need. Else, use a CMOS op-amp and large divider resistors to set gain.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
A couple of years ago I bought a couple of Hg battery replacements for cameras. Basically they're the size of the original battery and take a 1.5V buttons cell, with an LDO of some sort to drop the voltage appropriately. I don't remember the specifics.
Sure. Buy another mercury battery. They have much lower noise than semiconductor regulators, better output stability than other battery types, and some (small) types are still available, last time I heard, for compatibility with old gear.
An alkaline battery can make a nice 0.5 Hz triangle wave generator, because there's a gas discharge and venting occurs. If you really want to get the precision, accuracy, and low impedance of a mercury battery, resign yourself to paying for proper disposal.
For a nearby bunch of people breathing out diminished O2, it'll be a few minutes (for diffusion). For a wind gust that lowers the local air pressure, only a few milliseconds. And for local barometric changes, there will be corresponding shifts in the average output voltage from day to day.
Heaven only knows what effect ozone or laboratory gasses might have.
If the requirement is just for a stable reference voltage, there are stabilized ICs that can handle the task. If you need low noise, and low output impedance at a broad frequency range, and good voltage stability, it's hard to beat a mercury cell, even just the 'regular' ones, not the Weston cells.
The camera-battery solutions are not reference-grade sources.
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